Method for concurrently producing at least a pair of semiconductor structures that each include at least one useful layer on a substrate

ABSTRACT

A method for concurrently producing at least a pair of semiconductor structures that each include at least one useful layer on a substrate. The method includes providing an initial structure that includes a useful layer having a front face on a support substrate. Atomic species are implanted into the useful layer to a controlled mean implantation depth to form a zone of weakness within the useful layer that defines first and second useful layers. Next, a stiffening substrate is bonded to the front face of the initial structure. The first useful layer is then detached from the second useful layer along the zone of weakness to obtain a pair of semiconductor structures with a first structure including the stiffening substrate and the first useful layer and a second structure including the support substrate and the second useful layer. The structures obtained can be used in the fields of electronics, optoelectronics or optics.

BACKGROUND ART

This invention generally relates to a method of concurrently producingat least two structures, each having at least one useful layer on asubstrate, for applications in the fields of electronics,optoelectronics or optics. In particular, the method includes providingan initial structure that includes a useful layer having a front face ona support substrate, implanting atomic species to form a zone ofweakness within the useful layer, bonding a stiffening substrate isbonded to a front face of the initial structure, and detaching a firstuseful layer from a second useful layer along the zone of weakness toobtain a pair of semiconductor structures. The first structure includesthe stiffening substrate and the first useful layer and the secondstructure includes the support substrate and the second useful layer.

Several layer transfer methods are known. One concerns implanting atomicspecies under the surface of a source substrate to create a zone ofweakness which delimits a thin layer. The next step is to contact thefree face of this thin layer with a support substrate, then to detachthe thin layer from the remainder of the source substrate and totransfer it to the support substrate. A description of this type ofmethod can be found in the art with reference to the method known underthe registered trademark “SMART-CUT®”. Use of this method results ingenerating a source substrate remainder that can be recycled and reusedduring a future layer transfer. However, this process involves polishingand finishing operations that can be long and costly, due to both thecost of the materials used and the time spent on them. In addition, forsome extremely hard materials such as silicon carbide, theaforementioned recycling steps can prove to be very long and difficult.

Another known layer transfer method is called “Bond and Etch BackSilicon on Insulator” (“BESOI”). This technique involves a burning-inmethod and/or chemical etching treatment via chemical attack used aftermolecular bonding a source substrate to a support substrate. The freesurface (or rear face) of this source substrate is then polished until athin layer of desire thickness is obtained on the support. It is to benoted that such a method destroys the majority of the source substrateas each structure is made, so this technique is not economically viable,especially when the thin layer material is expensive.

Lastly, Silicon on Insulator (“SOI”) type materials include a layer ofthick silicon covering a buried layer of silicon dioxide (SiO₂) and atransferred superficial layer of silicon, and the same problemsconcerning recycling exist for the silicon material used to form thetransferred layer. In addition to the aforementioned recycling problems,it is difficult to transfer very thin layers, meaning layers that areless than 100 nanometers (100 nm) thick when using the SMART-CUT® typemethod. Indeed, thin layers transferred in such manner have numerousdefects, such as blisters. The defects may be due to, for example,treatments used to strengthen the bonding interface between the thinlayer and the support substrate.

The problems concerning transferring very thin good quality layers alsoexist for SOI substrates. In particular, is noted that the transferredlayer of silicon if an SOI structure has defects when less than acertain thickness, for example 20 nm. The defects can increase if a hightemperature thermal treatment is also used. In this regard, referencecan be made to the article by Q.-Y. Tong, G. Cha, R. Gafiteau and U.Gösele, “Low temperature wafer direct bonding”, J. MicroelectomechSyst., 3, 29, (1994).

During thermal treatments, for example to strengthen the bondinginterface (which is known as “stabilizing”) after detachment occurs, agas is created in the bonding interface. In the case of a thick SOIsubstrate, the transferred layer is thick and fills the role of astiffener. In the case of a thin SOI substrate in which the transferredlayer and/or the oxide layer are thin, the aforementioned absorption andstiffening phenomena do not take place and use of a gas leads to poorbonding.

In addition, as described in published International Application No. WO01/115218, implantation of atomic species and detachment of the wafercreate defects that are principally concentrated on the inside of thelayer to be transferred. It has been observed that the thinner the layerthe poorer the quality that results.

SUMMARY OF THE INVENTION

A method for concurrently producing at least a pair of semiconductorstructures that each include at least one useful layer on a substrate.The method includes providing an initial structure that includes auseful layer having a front face on a support substrate. Atomic speciesare implanted into the useful layer to a controlled mean implantationdepth to form a zone of weakness within the useful layer that definesfirst and second useful layers. Next, a stiffening substrate is bondedto the front face of the initial structure. The first useful layer isthen detached from the second useful layer along the zone of weakness toobtain a pair of semiconductor structures with a first structureincluding the stiffening substrate and the first useful layer and asecond structure including the support substrate and the second usefullayer.

Advantageously, the method includes implanting by introducing atomicspecies through the front face of the useful layer to form the zone ofweakness. In addition, the useful layer is provided at a sufficientthickness to provide multiple first and second useful layers duringfurther processing. In a preferred embodiment, the technique includesrepeating the implanting, bonding and detaching steps on the usefullayers of the first and second structures to provide a third and fourthsemiconductor structures, with the third structure including a secondstiffening substrate and a third useful layer, and the fourth structureincluding a third stiffening substrate and a fourth useful layer. In avariation, the first and second useful layers are provided at sufficientthicknesses to provide multiple third and fourth useful layers duringfurther processing. Such structures are suitable for use in electronic,optoelectronic or optic applications.

In an advantageous implementation, included is at least one intermediatelayer in the initial structure between the useful layer and the supportsubstrate. In another variation, an intermediate layer is provided inthe second structure between the stiffening substrate and the firstuseful layer. Such intermediate layers are preferably made of at leastone of silicon dioxide (SiO₂), silicon nitride (Si₃N₄), a highpermitivity insulating material, diamond or strained silicon.

In another advantageous implementation, bonding is achieved by molecularadhesion. In addition, at least one of the support substrate, thestiffening substrate, or the useful layer is made of a semiconductormaterial. The support substrate and/or the stiffening substrate mayinclude at least one layer made of at least one of silicon, siliconcarbide, sapphire, diamond, germanium, quartz, yttrium-stabilizedzirconia or an alloy of silicon carbide. In addition, the useful layermay be made of at least one of silicon, silicon carbide, sapphire,diamond, germanium, silicon-germanium, a group III–V compound or a groupII–VI compound, and the support substrate may be made of asingle-crystal or poly-crystal silicon, the useful layer is made of asingle-crystal silicon, and the stiffening substrate is made of asingle-crystal or poly-crystal silicon.

The methods according to the invention allow at least one pair ofstructures to be formed at the end of each cycle using a single sourcesubstrate which can then be recycled. The present invention is thus moreeconomical to use and commercially feasible than known methods thatrecycle the source substrate. Moreover, as the cycles are repeated, anoperator can choose to use the same or different types of stiffenersubstrates, and can also choose to include one or more intermediate orinterposed layers. The technique according to the invention is thusflexible, allowing for different possible combinations of concomitantlyformed structures that include stacks of different layers.

Furthermore, depending on the parameters used to implant atomic species,it is also possible to create a zone of weakness such that the rear orsecond useful layers are very thin. For example, such thin layers may beless than 50 nanometers (50 nm) thick, whereas the neighboring frontuseful layers are much thicker. The thickness of the front useful layerassociated with that of the stiffener which is pressed against it allowsfor a later thermal annealing treatment that will not deform the rearuseful layer, and that will not cause blisters to form on the rearuseful layer. The result is that a much thinner rear useful layer can betransferred than presently possible using conventional methods. Yetfurther, it has been found that the implantation of atomic species stepscarried out on the substrates of the first rank or higher structuresconcentrate the defects in the front useful layers. Consequently, therear useful layers were not directly subjected to the implantation, andthus have defects linked to the implantation and to detachment thatextend over a lesser thickness in the detachment zone than that of thefront layer.

BRIEF DESCRIPTION OF THE DRAWINGS

Other aspects, purposes and advantages of the invention will becomeclear after reading the following detailed description with reference tothe attached drawings, in which:

FIGS. 1A to 1C illustrate the different steps of a method of producing astructure comprising a useful layer transferred to a support substrate;

FIGS. 2A to 2C are diagrams illustrating an alternative embodiment ofthe method represented in FIGS. 1A to 1C according to which a structureis obtained that includes a useful layer transferred to a substrate viaan intermediate layer;

FIGS. 3A to 3F are diagrams illustrating the different steps of a firstembodiment of the method of concurrently producing at least a pair ofstructures according to the invention;

FIGS. 4A to 4F are diagrams illustrating an alternative embodimentaccording to the invention of the method represented in FIGS. 3A to 3F;and

FIGS. 5A to 5F are diagrams illustrating the different steps of a secondembodiment of the method according to the invention.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

The present method includes forming a first structure 5 or 5′ obtainedby, for example, using one of the methods whose successive steps areillustrated in FIGS. 1A to 1C or 2A to 2C. These first structures arecalled rank 1 structures. In particular, FIG. 1A shows a sourcesubstrate 1 having a zone of weakness 4 that includes two parts: auseful layer 111 and a remainder layer 12 or rear part of the sourcesubstrate. This zone of weakness 4 is the “initial zone of weakness”.

The source substrate 1 has a “front face” 13 which will come intocontact with a support substrate 2 which will be described later.Advantageously, the source substrate 1 is made of a semiconductormaterial, in particular those commonly used for applications in thefield of electronics, optoelectronics or optics. For example, it couldbe made of silicon, silicon carbide, sapphire, diamond, germanium,silicon-germanium, III–V compounds or II–VI compounds. III–V compoundsare compounds wherein one of the elements appears in column III of theperiodic table and the other appears in column V, such as galliumnitride (GaN), gallium arsenide (AsGa) or indium phosphide (InP). II–VIcompounds are compounds wherein one of the elements appears in column IIof the periodic table and the other appears in column VI, such ascadmium telluride (CdTe). The source substrate 1 can also be a compoundsubstrate, which is a substrate composed of a solid part, for examplesilicon, having an overlying a buffer layer, for example, of silicongermanium (SiGe).

According to a first alternative embodiment, atomic species could beimplanted to obtain the initial zone of weakness 4. The phrase“implantation of atomic species” means any bombardment of atomic,molecular or ionic species, which introduces these species into amaterial, with a maximum concentration of the species located at apredetermined depth below the bombarded surface 13. Atomic species canbe implanted in the source substrate 1 by using, for example, an ionbeam implanter or a plasma immersion implanter. Preferably, implantationis carried out by ion bombardment. In addition, the ionic species thatis implanted is hydrogen. Other ionic species can be advantageously usedalone or in combination with hydrogen, such as rare gases (for examplehelium). Other variations of implantation techniques could also be used.

The implantation results in creating the initial zone of weakness 4 inthe volume of the source substrate 1 at an average depth of penetrationof the ions. The zone of weakness 4 extends substantially parallel tothe plane of the front face 13. The useful layer 11 extends between thefront face 13 and this zone of weakness 4. This step can be carried outby utilizing the method known under the registered trademark “SmartCut”.

The initial zone of weakness 4 can also be comprised of a porous layerthat is formed, for example, as described U.S. Pat. No. 6,100,166. Inthis case, the useful layer 11 may be obtained via epitaxy.

The support substrate 2 acts as a mechanical support and thus generallyhas a thickness of at least about 300 micrometers. It is preferably madeof any single-crystal or poly-crystal semiconductor material often usedin the aforementioned applications. The support substrate 2 can be asingle-layer solid substrate chosen for example from among silicon,silicon carbide, sapphire, diamond, germanium, quartz,yttrium-stabilized zirconia (ZrO₂(YO₃)) and an alloy of silicon carbide.

Referring to FIG. 1A, the support substrate 2 has one face 20, termedthe “front face” which receives the front face 13 of the sourcesubstrate 1. Then, as represented in FIG. 1B, the front face 13 of theuseful layer 11 is directly bonded onto the support substrate 2 withoutan intermediate layer. Advantageously, this bonding is carried out viamolecular adhesion. After a possible thermal annealing step, theremainder 12 is detached along the initial zone of weakness 4 byapplying stresses (see FIG. 1C). One of the following techniques may beused to detach the remainder: the application of mechanical or electricstresses, chemical etching or the application of energy, for example theuse of a laser, of microwaves, of an inductive heater, or a thermaltreatment in an oven. These detachment techniques are known to thoseskilled in the art and will not be described in any further detail, andcan be used alone or combined. A first rank structure (rank 1) 5 is thusobtained which includes the useful layer 11 transferred to a supportsubstrate 2.

FIGS. 2A to 2C illustrate an alternative embodiment of the method whichhas been described with regard to FIGS. 1A to 1C. This alternativetechnique differs in that at least one intermediate layer 3 is insertedbetween the useful layer 11 and the support substrate 2. For reasons ofclarity and simplicity, in FIGS. 2A to 2C and in FIGS. 5A to 5F only oneintermediate layer 3 has been represented, but additional intermediatelayers could be used. Advantageously, each of these intermediate layers3 are made of a material chosen from among silicon dioxide (SiO₂),silicon nitride (Si₃N₄), high permitivity insulating materials, anddiamond. It is also possible to have an intermediate layer made ofstrained silicon on a useful layer of relaxed silicon-germanium (SiGe).In the case where there are several intermediate layers 3, the latterlayer or layers can be either of the same nature or of a differentnature.

The intermediate layer 3 can be formed via chemical plating techniquesin vapor phase or any other technique known to those skilled in the art.Such techniques could be conducted on either the front face 20 of thesupport substrate 2, on the front face 13 of the source substrate 1, oron the two front faces. Such a technique is conducted prior to applyingor bonding these two substrates against one other. When the intermediatelayer 3 is an oxide layer, it can also be formed via thermal oxidationof one or the other of the two substrates 1 or 2. Irrespective of howthe intermediate layers 3 were formed, the free surface of the upperintermediate layer is bonded to the free surface of the substrate 1 or 2facing it, preferably via molecular adhesion.

The result of the alternative embodiment of the method is a first rankstructure 5′ that includes the source substrate 2, the useful layer 11,and the intermediate layer 3 inserted between them. The word“transferred” herein with regard to a first rank structure signifiesthat a useful layer is transferred to a support substrate via a methodcomprising at least one bonding step, with or without an intermediatelayer 3. According to another embodiment not shown in the figures, theuseful layer 11 can be transferred to the support substrate 2 via theBESOI technique, with or without an intermediate layer 3.

FIGS. 3A to 3C illustrate a complete cycle of steps of a firstembodiment of the present method, which results in a pair of structureseach comprising a useful layer transferred to a substrate. As shown inFIG. 3A, a zone of weakness 6 is formed on the inside of the usefullayer 11 of the previously obtained first rank structure 5, via theimplantation of atomic species according to the previously describedtechnique for obtaining a zone of weakness. Two layers are thus defined,namely a first or front useful layer 110 and a second or rear usefullayer 120 located between the front useful layer 110 and the supportsubstrate 2.

As shown in FIG. 3B, a stiffening substrate 71 is adhered to the freesurface 130 of the front useful layer 110, via bonding, preferably bydirect bonding via molecular adhesion. The last step illustrated in FIG.3C consists of detaching the stacks of layers obtained during theprevious step, along said zone of weakness 6. The layers are detached byapplying stresses according to techniques known to those skilled in theart, and previously described above with regard to FIGS. 1C and 2C.

Two structures 51 and 52 of a second rank are thus obtained. The firststructure 51 comprises the support substrate 2 and the rear useful layer120 and the second structure 52 comprises the stiffening substrate 71and the front useful layer 110. It is to be noted that the useful layer11 must have a sufficient thickness so that, after detachment, the twouseful layers 110 and 120 do not have any defects or blisters. Thethickness of the two useful layers 110 and 120 can be identical ordifferent according to the depth of implantation of the atomic speciesand therefore of the localization of the zone of weakness 6. It shouldalso be noted that the useful layer may be of sufficient thickness topermit multiple structures to be formed, which will be explained below.

It is possible to repeat the cycle of operations that has just beendescribed (that is, the creation of a zone of weakness, adhesion of astiffening substrate, and detachment along the zone of weakness) with atleast one of the structures 51, 52 of the second rank, or to both ofthem. Consequently, one or two pairs of third rank structures 511, 512,521, 522 (see FIG. 3F) are obtained.

As illustrated in FIG. 3D, the front face 140 of the useful layer 110 issubjected to implantation of atomic species to create a zone of weakness6, to define a rear useful layer 111 and a front useful layer 112. Asimilar method is used to continue processing with the second rankstructure 51, to obtain a front useful layer 122 and a rear useful layer121. The next step is to adhere or bond, via molecular adhesion, astiffening substrate 72 to the front face 140 of the front useful layer112 and a stiffening substrate 73 to the front face 150 of the rearuseful layer 122. As shown in FIG. 3F, the next step is to detach thetwo stacks of layers along the zone of weakness 6 so as to obtain fourthird rank structures.

The two third rank structures 521 and 522 issue from the second rankstructure 52 through use of a stiffener 71 and the rear useful layer 111for the first one, and the use of stiffener 72 and the front usefullayer 122 for the second one. The two third rank structures 511 and 512issue from the second rank structure 51 and include the stiffener 73 andthe front useful layer 122 for the first one, and the support substrate2 and the rear useful layer 121 for the second one.

It is then possible to repeat, if desired, the cycle of the threeoperations that has just been described. The starting structure could beat least one of the rank three structures or of following ranks. Thecycle should end when the useful layers transferred onto a substratereach a thickness above which an extra cycle would result in thetransfer of a poor quality useful layer, meaning one having defects orblisters.

FIGS. 4A to 4F illustrate an alternative embodiment of the presentmethod.

This method is different from that described with reference to FIGS. 3Ato 3F in that at least one interposed layer 8 and/or 8″, is insertedbetween the stiffening substrates 71 and 73, respectively and the usefullayer that faces it. It should be noted that the figures show only asingle interposed layer 8, 8″ for the purposes of simplification, butmore such layers could be used.

The interposed layer 8 or 8″ can be made, for example, via chemicalplating in a vapor phase or by any other layer plating technique knownto those skilled in the art. The interposed layers 8 or 8″,respectively, can also be obtained via oxidation of the stiffeningsubstrate 71 or 73, respectively. This plating can be carried out eitheron the stiffener prior to its application onto the useful layer, or ontothe latter, preferably prior to implanting atomic species to create thezone of weakness 6. The interposed layer 8 or 8″ is then bonded to thelayer facing it, preferably by molecular adhesion. For example, theinterposed layers 8, 8″ are made in a chosen material from among silicondioxide (SiO₂), silicon nitride (Si₃N₄), high permittivity insulatingmaterials, and diamond. In the case where there are several interposedlayers 8, 8″, these can be of the same nature or of different natures.

FIG. 4E shows that the stiffener 72 is directly bonded onto the frontuseful layer 112, meaning that it is bonded without an interposed layer.Four third rank structures are thus obtained, of which only two,reference numbers 521′ and 511′, comprise a stiffener, a useful layerand an interposed layer.

FIGS. 5A to 5F show a second embodiment of the present method. Thismethod is different from the first embodiment of FIGS. 4A to 4F in thatthe starting structure used is the first rank structure 5′, comprisingan intermediate layer 3 inserted between the useful layer 11 and thesupport substrate 2. In addition, an interposed layer 8′ is used betweenthe stiffener 72 and the front useful layer 112. This interposed layer8′ is of the same nature and is obtained in the same way as thepreviously described interposed layers 8 or 8″.

Two second rank structures 51′ and 52′, and then four third rankstructures 521′, 522′, 511′ and 512′ are obtained. Each of the thirdrank structures 521′m 52′ and 511′ include a stiffener, an interposedlayer 8, 8′ or 8″ and a useful layer. The fourth structure 512′ includesthe support substrate 2, the intermediate layer 3 and the useful layer121.

The expression “adhere a stiffening substrate onto a useful layer”herein encompasses the case where there is close contact between thestiffener and the useful layer, and the case where at least oneinterposed layer 8, 8′ or 8″ is present between them. In the differentmethods which have just been described, the expression “stiffeningsubstrate” refers to any type of substrate that acts as a mechanicalsupport and allows for the detachment of the useful layer from thesubstrate from which it issues.

The choice of the type and/or material (nature) of the stiffener 71, 72,73 depends on the final targeted application for the structure. Thestiffening substrates 71, 72, 73 can be chosen from among the examplesgiven for the support substrate 2.

The different alternative methods which have just been described allowat least one pair of structures to be formed at the end of each cyclefor a single source substrate 1 which can then be recycled. The presentmethods are thus more economical and commercially feasible than theknown methods which require recycling of the source substrate after eachstructure is created.

Moreover, upon each cycle repetition, an operator can choose to applythe same type or different stiffeners and can leave out all or includeat least one of interposed layer 8, 8′ or 8″. The methods are thusflexible, because there is the possibility of concomitantly forming thestructures comprising stacks of different layers.

Finally, depending on the parameters used to implant atomic species, itis also possible to create a zone of weakness 6 so that the rear usefullayers 120, 111 or 121 are very thin. For example, such thin layers maybe less than 50 nanometers (50 nm) thick, whereas the neighboring frontuseful layers 110, 112 or 122 may be much thicker. The thickness of thefront useful layer associated with that of the stiffener which ispressed against it allows for a later thermal annealing treatment thatwill not deform the rear useful layer, and that will not cause blistersto form on the rear useful layer. The result is that a much thinner rearuseful layer can be transferred than presently possible usingconventional methods such as the SMART-CUT® method.

Additionally, the implantation of atomic species steps carried out onthe substrates of the first rank or higher structures concentrate thedefects in the front useful layers 110 or 122. The rear useful layers120 or 121 were not directly subjected to the implantation and thus havea zone with defects linked to the implantation and to the detachmentextending over a lesser thickness in the detachment zone than that ofthe front layer.

The following is a description of an example of the present method withreference to FIGS. 5A to 5F.

EXAMPLE 1

The first rank structure used here is a SOI substrate type structure 5′that includes a support substrate 2 of single-crystal silicon, anintermediate layer 3 of silicon dioxide SiO₂ having a thickness of 20nm, and a useful layer 11 of single-crystal silicon having a thicknessof 1.5 μm. A zone of weakness 6 is created by implanting hydrogen ionsbased on an implantation energy of about 150 keV and an implantationdose of about 6·10¹⁶H⁺/cm². A rear useful layer 120 is thus createdhaving a thickness of 20 nm. A single-crystal silicon stiffener 71having an interposed layer 8 of silicon dioxide SiO₂ of a thickness of20 nm is then applied. The two structures are then detached along thezone of weakness 6 to simultaneously obtain a pair of SOI substrates 51′and 52′. The cycle of the operations is then repeated using the secondrank SOI substrate 52′ as a starting structure.

Once the surfaces have been prepared, the front useful layer 1112 has athickness of about 0.6 microns and the rear useful layer 111 has athickness of about 0.6 microns. When a single-crystal silicon stiffener72 covered in a layer of silicon dioxide 8′ of a thickness of 20 nm (20nanometers) is used, two third rank SOI substrates 521′ and 522′ areobtained after detachment that have respective useful layers 111 and 112that are about 0.6 microns thick.

1. A method for concurrently producing at least a pair of semiconductorstructures each including at least one useful layer on a substratecomprising: providing an initial semiconductor structure that includesan initial useful layer on an initial substrate; implanting atomicspecies into the initial useful layer to a controlled mean implantationdepth to form a zone of weakness within the useful layer that definesfirst and second useful layers; bonding a stiffening substrate to afront face of the initial structure; and detaching the first usefullayer from the second useful layer along the zone of weakness to producea pair of semiconductor structures with a first semiconductor structureincluding the stiffening substrate and the first useful layer and asecond semiconductor structure including the initial support substrateand the second useful layer, wherein the first useful layer and thesecond useful layer have a thickness such that both the firstsemiconductor structure and the second semiconductor structure are eachindividually suitable as an initial semiconductor structure from which afurther pair of semiconductor structures can be formed by the steps ofimplanting, bonding and detaching.
 2. The method of claim 1 furthercomprising selecting the mean implantation depth so that both the firstsemiconductor structure and the second semiconductor structure are eachindividually suitable as an initial semiconductor structure from which afurther pair of semiconductor structures can be formed by the steps ofimplanting, bonding and detaching.
 3. The method of claim 1 furthercomprising selecting the thickness of initial useful layer so thatmultiple first and multiple second useful layers can be produced duringfurther processing.
 4. The method of claim 1 which further comprisesrepeating the implanting, bonding and detaching steps on the seconduseful layer of the second semiconductor structure to provide a thirdand fourth semiconductor structures, with the third structure includinga third stiffening substrate and a third useful layer, and the fourthstructure including a fourth stiffening substrate and a fourth usefullayer.
 5. The method of claim 1 wherein the initial semiconductorstructure is a semiconductor material source substrate or a compoundsubstrate.
 6. The method of claim 1 wherein the initial substratecomprises bulk material.
 7. The method of claim 1 wherein the implantingincludes introducing atomic species through the front face of the usefullayer to form the zone of weakness.
 8. The method of claim 1 whichfurther comprises repeating the implanting, bonding and detaching stepson the first useful layer of the first semiconductor structure toprovide a third and fourth semiconductor structures, with the thirdstructure including a third stiffening substrate and a third usefullayer, and the fourth structure including a fourth stiffening substrateand a fourth useful layer.
 9. The method of claim 8 further comprisingselecting the thicknesses of the first and second useful layers so thatmultiple third and multiple fourth useful layers can be produced duringfurther processing.
 10. The method of claim 8 wherein all semiconductorstructures are suitable for use in electronic, optoelectronic or opticapplications.
 11. The method of claim 1 which further comprises at leastone intermediate layer in the initial structure between the useful layerand the support substrate.
 12. The method of claim 11 wherein theintermediate layer is at least one of silicon dioxide (SiO₂), siliconnitride (Si₃N₄), a high permitivity insulating material, diamond orstrained silicon.
 13. The method of claim 1 which further comprisesproviding an intermediate layer in the second structure between thestiffening substrate and the first useful layer.
 14. The method of claim13 wherein the intermediate layer is at least one of silicon dioxide(SiO₂), silicon nitride (Si₃N₄), a high permitivity insulating material,diamond or strained silicon.
 15. The method of claim 1 wherein thebonding is achieved by molecular adhesion.
 16. The method of claim 1wherein at least one of the support substrate, and the stiffeningsubstrate is made of a semiconductor material.
 17. The method of claim 1wherein the support substrate includes at least one layer made of atleast one of silicon, silicon carbide, sapphire, diamond, germanium,quartz, yttrium-stabilized zirconia or an alloy of silicon carbide. 18.The method of claim 1 wherein the stiffening substrate includes at leastone layer made of at least one of silicon, silicon carbide, sapphire,diamond, germanium, quartz, yttrium-stabilized zirconia or an alloy ofsilicon carbide.
 19. The method claim 1 wherein the useful layer is madeof at least one of silicon, silicon carbide, sapphire, diamond,germanium, silicon-germanium, a group III–V compound or a group II–VIcompound.
 20. The method of claim 1 wherein the support substrate ismade of a single-crystal or poly-crystal silicon, the useful layer ismade of a single-crystal silicon, and the stiffening substrate is madeof a single-crystal or poly-crystal silicon.
 21. The method of claim 1wherein the useful substrate is molecularly bonded to the supportsubstrate.